A population-based case-control study of non-Hodgkin's lymphoma (NHL) that included nearly 1600 patients with NHL and more than 2500 control participants was conducted by the Principal Investigator and colleagues in the San Francisco Bay Area between 1988 and 1995. NHL cases were obtained using rapid case ascertainment by the Northern California Cancer Center and control participants were identified using random digit dial and the Healthcare Financing Administration files. Pathology materials for the NHL patients included in the study were reviewed and classified of this study are: 1) to evaluate the association between exposure data collected in this large study and subtypes of NHL defined using the Working Formulation with emphasis on the investigation of risk factors found to be of importance in the main analyses of all NHL; and 2) to complete detailed analyses to investigate the association between risk for NHL and occupational and chemical exposures including Agent Orange, reproductive and hormonal exposures among women , support for hypotheses that indicated there are etiologic differences across NHL subtypes that can be characterized by a unique set of associated risk factors. Differentiation of risk factors by NHL subtypes will provide important clues to detailed analyses between exposures of interest and risk for NHL with adjustment for potential confounders and effect modifiers. These data may explain inconsistencies in results from earlier NHL studies constrained by limited sample size and exposure data. They also may provide important additional information about the role of exposures that alter Th1 or Th2 pathways and the process of lymphomagenesis. These data will be used as preliminary results for a larger Bay Area study of lymphoma.